The present invention relates to a vector-sort drafting method of an automatic drafting machine, in which a line drafting head is sent relatively along a X-axis direction to a sheet of paper, and along a Y-axis direction transversing the paper sheet, and a writing instrument held in the line drafting head draws a predetermined pattern on the paper sheet.
As shown in FIGS. 5 to 7, which illustrate a sheet driven type automatic drafting machine, the machine comprises a Y rail 6 bridging between leg members 2 and 4, a platen 8 situated below the Y rail 6 and secured between the leg members 2 and 4, a line drawing head 16 movably connected to the Y rail 6 through a Y carsol 10, a pen holder 12 connected to an elevating and lifting drive apparatus in order to hold a writing instrument such as a pen 14 therein, a drive roller 22 and a pressing roller 18 for gripping therebetween the paper sheet 20 sliding on the platen 8 for feeding the sheet in the X direction along the platen 8, a drafting roller 24 having substantially the same circumferential speed as that of the drive roller 22 and being driven along the same direction as that of the drive roller, a X motor for driving the drive roller 22 and the drafting roller 24, a Y motor for driving the line drawing head 16 along the Y rail 6, and a controller stored in a casing (not shown) situated below the platen 8 so as to control the elevation drive control apparatus placed within the line drawing head 16.
According to the conventional automatic drafting machine, the paper sheet 20 is transferred along the platen 8 in the X direction on the basis of the pattern drafting data transferred from the host computer to the controller and the line drawing head 16 is moved along the Y rail 6 transverse to the platen 8 to draft fixed patterns on the paper sheet 20 by a pen 14.
The flat bed type automatic drafting machine as shown in FIG. 8 has been well known.
On the basis of the drafting data transferred from the host computer to the controller, the automatic drafting machine moves the Y rail 28 repeatedly and parallely along the table 26 in the X direction. In addition, the line drafting head 16 is moved along the Y rail 28 so as to traverse the paper sheet 20 on the table 26. Thus, it is possible to draft a predetermined drawing on the paper sheet 20 by using the pen 14.
When there are vector segments L.sub.1, L.sub.2, and L.sub.3 as shown in FIG. 8 in the drafting operation above, these vector segments are drafted according to the conventional vector sort method in order from a point A to a point B, from a point D to a point C, and from a point E to a point F with respect to an origin O. That is, the shortest distance from the XY co-ordinates is selected and a line to be drawn is drafted.
The drive roller and pressure roller of the conventional paper drive type automatic drafting machine grips a paper sheet between them. Alternative or reciprocating motion of the paper sheet along the platen in the X direction is done by a forward and reverse rotation of the drive roller so as to carry out draftings of patterns on the paper sheet. It is apt to make the paper sheet damaged by friction of the drive roller after a drafting operation for a long time and consequently the paper sheet is likely to shift or slip out of place.
That is, according to the conventional vector sort method, it is possible to shorten the drafting time, but it is not possible to shorten the repeating movement distance of the paper sheet in the X direction. As a result, the paper sheet is apt to be disadvantageously damaged according to the prior art.
According to the flat bed type automatic drafting machine, it has not been possible to shorten the reciprocating movement distance of the Y rail in the X direction. Consequently, large noise due to movement of the Y rail occurs.
It is the purpose of the present invention to solve the problems of the conventional automatic drafting machine.